In my commonly assigned copending application Ser. No. 403,706, filed July 30, 1982, there has been disclosed a telephone switching exchange consisting of a plurality of modular units where each modular unit comprises switching means and control means, the latter being formed by a microprocessor.
In known systems of this type, wherein a plurality of units each comprising a microprocessor exchange messages, one of these systems provides for equipping each microprocessor with a software structure adapted to cyclically interrogate the reception channels in order to detect whether one of the modular units in the system is providing a message destined therefor.
According to a further arrangement, the microprocessor of the modular unit ready to emit a message generates a request to interrupt the operative program of the microprocessor associated with the modular unit to which the message is addressed. Then, when the microprocessor of the receiving modular unit accedes to the interruption request, it recovers the message.
Such procedures for message transfer have the drawback that they require the engagement of at least one of the two microprocessors involved in the operation until it has completed the recovery of a message by the microprocessor of the receiving modular unit. Thus, the time spent by the microprocessors to transfer messages is substantial to the proportionate degree that it reduces their availability for performing other functions, such as processing operations etc.